Borosilicate glass is a well-known glass that has a low coefficient of thermal expansion (CTE) 33×10−7/° C. and high chemical durability (i.e., resistance to acidic and alkaline reagents). As a result, borosilicate glass has become an important component in many types of laboratory equipment that require chemical durability.
However, powdered borosilicate glass (borosilicate glass frit) undergoes devitrification (i.e., formation of cristobalite, tridymite, and/or quartz crystals that lead to a decrease in glass properties) during sintering at between about 700-800° C. Crystal formation with high CTE lowers the mechanical strength of the sintered glass product. Lower mechanical strength is also due to the volume change associated with the phase transformation from an amorphous state to the crystal state. Thus, when powdered borosilicate glass is used to make frit layers on a substrate having a low CTE, devitrification increases global CTE of the frit layer and thereby causes cracks to form.
One potential solution to overcome devitrification in powdered borosilicate glass is to add an inhibitor oxide such as alumina to the powdered borosilicate glass. The addition of the alumina tends to inhibit the formation of high expansion crystals. The addition of alumina, however, causes the sintering ability of the frit glass to decrease. In addition, the fluidity of the frit glass is decreased during sintering when alumina has been added.
Thus, a heretofore unaddressed need exists in the industry to form a glass frit that addresses the aforementioned deficiencies and/or inadequacies.